1. Field of the Invention
The present invention relates to an electronic device which can be attached to an industrial product and in which the manufacturer of the industrial product can set a use period of the industrial product.
2. Description of the Related Art
The lifetime of any industrial product depends how its major components are degraded with time. The components differ from one another in terms of lifetime. Hence, the industrial product may be used after its valid use period as long as the product works well, even if some of its components have ceased to function.
As long the use of as such an industrial product causes no safety problems, the user need not be worry so much. Assume that the component that has first ceased to function is a safety device. This means that the user is using a product without a safety device. It should be noted that the safety device may be related to gas-leakage detection, car braking or fire prevention.
A technique of limiting the use period of a product by using a timer is disclosed in, for example, U.S. Pat. No. 4,588,901. A timer may be mounted on an electronic board, so that the product may be disabled upon laps of, for example, ten years. In this case, however, the product can be used longer than ten years only if power supply is disconnected from the timer, thereby stopping the timer.
To prevent such an overuse of a product, it is desired that an electronic device be provided, which can control, without using batteries, the lifetime of the microcomputer or electronic board incorporated in the product.